Speciation of Mercury and Heavy Metals in Hg-contaminated Soils from Oak Ridge TN - 19426
- Department of Chemistry, Physics and Atmospheric Sciences, Jackson State University, Jackson, MS (United States)
Mercury is present in various forms in the environments. Mercuric compounds, Hg(II) are found predominant species in soil and water, while elemental mercury, Hg0 is the major species in the atmosphere, and organo-mercury is present mostly in food-chain. The speciation of Hg is important to understand its mobility, bioavailability in soils, sediments and biota and potential toxicity on human and environmental health. A catastrophic Hg spill occurred at the Y-12 National Security Complex (Y-12 Plant) at the Oak Ridge Reservation of the Department of Energy (DOE) in 1960's that contaminated facilities, soil, sediment, surface water, and groundwater within the boundaries of the Y-12 Plant and the downstream environment along the East Fork Poplar Creek (EFPC) at the city of Oak Ridge. It is estimated that 350,000 kg of Hg was released to the environment. The EFPC floodplain soils were reported to contain predominantly cinnabar (HgS) form, but other inorganic and organic Hg species, including Hg0 , HgCl{sub 2}, Hg{sub 2}Cl{sub 2}, HgO and CH{sub 3}Hg{sup +} have been found within the Y-12 Facility boundaries and the 23-km long contaminated EFPC. Over the last 25 years, Hg fluxes from the Y-12 Plant have been reduced by various remediation efforts, nonetheless Hg concentration in water and fish have not declined due to the persistent leaching of Hg from contaminated floodplain soils and sediments. In this work, we performed total elemental analyses and Hg speciation in the floodplain soils and sediments collected along EFPC in Oak Ridge, TN. The objective of the study was to elucidate the distribution of Hg in floodplain soil fractions and the relation with metals including arsenic, copper, zinc and lead. Total elemental; characterization was performed by ICP-MS analysis after with HNO{sub 3} and HF dissolution. Sequential extractions were carried out to extract water-soluble (F1), cation-exchangeable (F2) fractions and those bound to carbonates (F3), reducible oxides (F4) (Mn-oxides), organic matter (F5), amorphous (F6) and crystalline iron oxides (F7) and the residual fraction (F8) containing elemental Hg, non-cinnabar Hg and humic acid-bound Hg. Preliminary studies were conducted with artificially spiked and incubated soils as well as soils contaminated with enriched {sup 200}Hg isotope. The results indicated that Hg is predominantly associated with organic matter, amorphous iron and crystalline oxides and the residual fraction. The total Hg in the first four fractions (F1, F2, F3, and F4) were about 1% of the total Hg, while Hg was found equally bound to organic matter (F5) and crystalline Fe-oxides (F7) that accounted about 20% of total Hg. The Hg associated with amorphous iron oxides (F6) accounted as much as 26% of the total Hg and non-cinnabar Hg accounted about 24% of total Hg (non-cinnabar Hg). The results also indicated positive correlation for As, Cu, Pb and Zn levels with those of Hg. Most As was associated with amorphous Fe-oxides. Cu and Pb were dominant both in organic matter and amorphous oxide fractions. Zn was mostly bound to amorphous Fe-oxide but significant amount of Zn was also found to be associated with organic matter and crystalline Fe-oxides. (authors)
- Research Organization:
- WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
- OSTI ID:
- 23005325
- Report Number(s):
- INIS-US-21-WM-19426; TRN: US21V1252045659
- Resource Relation:
- Conference: WM2019: 45. Annual Waste Management Conference, Phoenix, AZ (United States), 3-7 Mar 2019; Other Information: Country of input: France; 17 refs.; available online at: https://www.xcdsystem.com/wmsym/2019/index.html
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ARSENIC
CARBONATES
COPPER
ECOLOGICAL CONCENTRATION
GROUND WATER
HEAVY METALS
HUMIC ACIDS
HYDROFLUORIC ACID
IRON
IRON OXIDES
MERCURY
MERCURY CHLORIDES
MERCURY OXIDES
MERCURY SULFIDES
OAK RIDGE RESERVATION
ORGANIC MATTER
REMEDIAL ACTION
SEDIMENTS
SULFIDE MINERALS
TOXICITY
Y-12 PLANT
ZINC